The detection of drowsiness is of importance because drowsiness impairs the ability of operators of a wide range of equipment including motor vehicles, aircraft and boats as well as industrial equipment
WO 03/039358 disclosed an alertness monitor that used infra red light to measure the amplitude and velocity of eyelid and eye movements to derive a measure of Drowsiness on a scale. This monitor sought to provide a real time alertness monitor that can provide a calibrated measure of the operator's alertness.
WO 2007/016739 discloses spectacles for use in the eye monitoring system of WO 03/039358, which include a pair of ocular frames and a sensor unit adapted to be positioned adjacent an eye of the wearer. A nose bridge connects the ocular frames and incorporates an adjustment mechanism for adjusting the vertical position of the sensor unit relative to the eye. A frame arm extends from the outer edge of each ocular frame and is adapted to fit over the ear of a wearer. The sensor unit incorporates two infra red emitters at different angles and an infra red detector recessed into the surface of the unit to reduce the proportion of signal received by said detector which is not from the signal emitter reflected by the eye or eyelids. There is a recent concern with the problem of driver inattention and distraction, not just drowsiness. By distraction they mean displacement of the driver's focus of visual attention from the driving task, either to a non-visual task (eg talking to other people in the vehicle, or the use of mobile phones), or to an alternative, visual task that reduces driving safety temporarily (reading a map or navigation system, adjusting a CD player or radio, etc). Thus, driver distraction is concerned with attention that is focused inappropriately, in direction and duration, for safe driving. There has been a number of attempts to deal with inattention by drivers.
EP 168788 discloses a method of monitoring inattentiveness by monitoring the steering of the vehicle.
USA patent application 2005/0030184 discloses a vehicle control subsystem that senses a level of the drivers attention compared to the current state of the vehicle.
USA patent application 2007/0008151 discloses a method of detecting drowsiness and or inattention by analysing head movements or head movement reactions of the driver.
U.S. Pat. No. 7,344,251 discloses a method of determining mental alertness by monitoring the subjects point of gaze and pupillary movements and pupillary response in performing a task, analysing the responses and calculating an alertness score.
It is an object of this invention to provide an improved method of monitoring overall alertness including drowsiness and inattention.